Radio frequency identification chip/antennas combined with radio frequency identification interrogators (collectively, RFID systems) have been utilized in numerous industrial and retail settings for tracking of inventory and capital equipment. Historically, some applications include inventory management in warehouse operations, unit tracking of retail items such as clothing and shoes, uses associated with SMART debit cards, garment tracking in retail and dry cleaning industries, and on livestock to record individual animal location. RFID tracking devices have also been described in healthcare settings for continuous tracking of patient, physician and/or health care worker location within medical centers, asset control for hospital capital equipment, and as a mechanism to track access to controlled areas such as pharmacy.
RFID devices can be programmed to store relatively large amounts of information as compared to traditional bar codes. Unlike traditional bar codes that typically cannot be changed once applied, some RFID devices possess READ/WRITE capability that enables characteristic information about each specific unit of interest to be recorded on the RFID tag during use, either by addition, subtraction or modification of previously encoded information. These modifications can be either written only once or many times depending on the RFID system used.
For most clinical and environmental test systems, existing systems require that information specific to calibration, control, discrimination cut-off values for determination of positive/negative, notification to the user of result in/out of expected range, and other test-specific information be manually input at some defined frequency and/or with each lot number. The approach used by such systems has been for the input of this information to the analytical instrument to be performed by manual intervention including manual key-punch, and/or bar-code, or magnetic-type reader.
Because the relationship of the single-use test device or specimen cup is by nature transitory and such device is either discarded following use or washed or cleansed by some process, prior system did not provide a mechanism for positive tracking of the test device other than by barcode. The bar code technology requires positive line-of-sight and may be adversely affected by the test contents, reagents and/or by physical handling. RFID devices obviate the strict optical direct “line of sight” requirements of bar-code systems.
RFID systems are typically comprised of 1) relatively small (typically 2–625 square millimeters) radio frequency tags that can be permanently or semi-permanently attached to items of interest, 2) a transceiver or interrogator (RFID reader) to read-from and/or write-to the tag, and in some cases, 3) an associated computerized data management system to process discrete information obtained by the interrogator.
In conventional RFID inventory control type systems, specific asset information is encoded onto a series of RFID tags that are attached to the items of interest as required for tracking purposes. On passive tag designs, the items of interest containing the tags are brought near a base station transceiver or interrogator that transmits an excitation radiowave to the powering circuitry on the tag as described. An RFID transceiver or interrogator transmits an amplitude-modulated radio signal followed by a continuous wave radio signal to each tag. The tag modulates the continuous wave signal using modulated back-scattering where the tag's antenna is electrically switched by the tags modulating signal from being an absorber of radiofrequency radiation to a reflector of the energy with the tag's information encoded onto the continuous wave radio signal. Such inductive coupled tags do not have self-contained batteries, have zero maintenance and virtually unlimited lifespan. However, their operating range is limited by the associated antenna and repeater electronics compared to other active tag designs.
In many tracking designs, the tag circuitry communicates the stored information from the tag to the base station that receives and decodes the information. Once encoded, a RFID reader demodulates the incoming continuous wave signal and decodes the information from the tag specific to the associated item. RFID readers are well known in the art and are commercially available for a variety of manufacturers including Motorola and Hitachi. A computer system that interfaces with the reader to direct interrogation of each tag and/or to record pertinent information for each event and for data processing may also be incorporated in an RFID system.